It was real all along.
Hate to disagree with you my boy, but I really, really hope that isn't the case.
As he is right now, Kylo Ren is a really interesting villain character, and in one way I would say he's more interesting than Vader. Vader is motivated to kill his master because since he's lost so much he can't bear to lose his son as well, while Kylo is motivated to do it because its a further progression of his strength in the dark side. Having a poorly rushed redemption arc after all that he's done to hurt the protagonists would feel disingenuous at this point. I'm not saying that it couldn't be done, but it would have to be done really well to convince me.
Also this movie is already similar enough to Dark Empire that I'm willing to bet that the Rey in the trailer is just an evil clone. They did with Luke in the Thrawn trilogy, and since Disney has a habit of robbing Legend's grave I wouldn't put it past them to reuse that plot point.